1. Field of the Invention
This invention relates to a novel tetrahedral codon stereo-table which points out a better arrangement of DNA/RNA codons and it is highly useful in the field of genetic engineering. The stereo-table is an instructive tool for effective learning about the natural codon system, the corresponding L-amino acid sequence and the like.
2. Description of the Prior Art
It is well-known that progress in genetic engineering is remarkable as can be seen by gene manipulation. The technique thereof has been widely and practically available in the fields of medicine, foods, new living forms and the like. The importance of a codon system and a genetic mechanism must be emphasized. Learning about the codon system or genetic engineering is now indispensable for every scientist who engages in biology or biotechnology as well as for government officers or environmentalists.
Heredity is derived from the fact that proper amino acids, peptides and proteins are systematically connected and duly taken into living bodies. Genetic information is exactly inherited from ancestors to the descendant, because an organism is duly shared with the proper genes of the ancestors. Mechanism of polypeptide formation is now examined on a bio-molecular level, i.e. transcription of ribonucleic acid (RNA) from the corresponding deoxyribonucleic acid (DNA) inherent in the organism, successive connection of amino acids and formation of proper polypeptide chain in the proper order. In brief, heridity of an organism starts from DNA functions of the ancestors. Such a gene code is transmitted and controlled by the sequential DNA chains with 20 kinds of L-amino acids, the function of resultant peptide chain, a three-dimensional structure of protein and the like, so that every arrangement of three consecutive nucleotides (gene triplet) can be translated into an action program to run or terminate the connection of one L-amino acid at the peptide terminal. Amino acids are connected one by one through the RNA code to form the necessary polypeptide chain in the due order inherited. DNA nucleotides are connected with a phosphate chain of 4 nucleosides, i.e. adenosine (A), cytidine (C), guanosine (G) and thymidine (T), while RNA nucleosides consist of A, C, G and uridine (U) instead of DNA's T.
There are 4.sup.3 =64 phases of the gene triplets, because the 3 nucleotides for one triplet can be arbitrarily selected thrice from the 4 kinds of DNA/RNA nucleotides. Natural 20 L-amino acids are expressed by their codon teams having one to six phases. The relationship between said codons and the corresponding L-amino acids has been traditionally shown only by the attached table.
TABLE __________________________________________________________________________ 64 RNA Codons and the Corresponding 20 Amino Acids U C A G __________________________________________________________________________ U UUU Phe UCU UAU Tyr UGU Cys UUC (F) UCC Ser UAC (Y) UGC (C) UUA Leu UCA (S) UAA Ocher UGA Opal UUG (L) UCG UAG Amber UGG Trp(W) C CUU CCU CAU His CGU CUC Leu CCC Pro CAC (H) CGC Arg CUA (L) CCA (P) CAA Gln CGA (R) CUG CCG CAG (Q) CGG A AUU ACU AAU Asn AGU Ser AUC Ile ACC Thr AAC (N) AGC (S) AUA (I) ACG (T) AAA Lys AGA Arg AUG Met(M) ACG AAG (K) AGG (R) G GUU GCU GAU Asp GGU GUC Val GCC Ala GAU (D) GGC Gly GUA (V) GCA (A) GAA Glu GGA (G) GUG GCG GAG (E) GGG __________________________________________________________________________
Such a traditional RNA table, however, has a lot of drawbacks in learning. While three L-amino acids, leucine (abbreviated as Leu/L), arginine (Arg/R) and serine (Ser/S) are expressed each by the respective codon hexaphases, the phase allocations seem quite irregular in the table. It is least convenient or serving for genetic scientists to learn about or contemplate an updated gene mechanism. When learners wish to apply said table to DNA codon system, they have to convert RNA uridine (U) into DNA thymidine (T) during their studying or thinking.